Gille Escoib or Gilleasbaig of Menstrie is the earliest member of the Campbell family to be attested in contemporary sources, appearing in royal charters dating to the 1260s.
However, nothing is known of this man, nor of the 4 or 5 generations of his ancestors who constitute the probable historical section these genealogies preceding Dubhghall.
He was granted the estates of Menstrie and Sauchie in Clackmannanshire (but then under the supervision of the sheriff of Stirling).
[2] The genealogies, and indeed later 13th century patronymic appellations, tell us that Gilleasbaig was the father of Cailean Mór, probably by marriage to the Carrick noblewoman, Afraig, a daughter of Cailean of Carrick.
[3] The name Gilleasbaig is a modernization of "Gilla Escoib" (with a variety of related spellings, such as Gille Escoib), and is often rendered as "Archibald" in English or occasionally "Gillespie" or "Gillespic".